In the 1960 WHO monograph, Kelly and Snedden estimated a
population of 200 million in the world to be suffering from goitre (Clements
et al., 1960 p.28). More recent estimates exceed this figure in spite of
extensive iodization programmes. The worldwide distribution of Iodine Deficiency
Disorders (IDD) in developing countries is shown in Fig. 1 in "Introduction and
Policy Implications" Section.

There is consensus that some 800 million people are at risk of
IDD from living in iodine-deficient environments, with 190 million suffering
from goitre and more than 3 million with overt cretinism, while millions more
suffer from some intellectual deficit (Hetzel, 1987 p.7).

In the Southeast Asia Region eight countries - Bangladesh,
Bhutan, Burma, India, Indonesia, Nepal, Sri Lanka and Thailand - all have
significant IDD problems. Altogether in these eight countries, it has been
estimated in the light of extensive surveys that 277 million are at risk of IDD,
some 102 million have goitre, 1.5 million are cretins, and many more suffer from
some degree of mental or motor impairment as a result of iodine deficiency
(Clugston and Bagchi, 1985).

In the People's Republic of China, it has been estimated that
some 300 million are living in iodine-deficient regions and therefore exposed to
the risk of IDD. Only one-third of this population was reported as adequately
covered by control programmes in 1982 (Ma et al., 1982)1.
Fever data are available from Africa, but the indications are that the IDD
problem is widespread (see Section 3.3). In Latin America the problem persists
in Bolivia, Peru, Ecuador and many other countries, in spite of attempts to
control IDD with iodized salt (WHO, 1984). IDD persist in many European
countries including Germany (both F.R.G. and G.D.R.), Romania, Poland, Spain,
Portugal and Italy (European Thyroid Association, 1985).

Detailed information from the major regions follows.
Individual country programmes are considered in Section 6.

3.1 EUROPEAN REGION

The report of the Subcommittee on Goitre and Iodine Deficiency
in Europe of the European Thyroid Association (ETA) makes the following comment:
"The Scientific Community of the ETA has the obligation to contribute to the
eradication of endemic goitre and iodine deficiency in Europe. With the
available knowledge it seems an anachronism that endemic goitre in Europe still
prevails (European Thyroid Association, 1985). The report goes on to note the
lack of information. The available data were confined largely to local areas.
The report was nevertheless made because even with these limitations the data
were "alarming enough".

The data are summarized in Table 6. Available information is
confined to goitre prevalence, urinary iodine excretion surveys and prophylactic
measures. The report notes, however, that assay of TSH in neonatal screening
programmes is "a sensitive parameter for iodine deficiency".

Some data on neonatal levels of serum T-4 and TSH in Greece
have been reported (Beckers et al., 1981) and are shown in Table 7. The
table indicates a lowered level of serum T-4 and raised TSH in the endemic area
where there is moderate iodine deficiency without clinical endemic cretinism.
Urinary iodine levels are in the range of 13.4 -33.9 mcg/d.

TABLE 7

NEONATAL THYROID FUNCTION IN GREECE

No.

T-4 (mcg %)

SD

TSH (mcgU/ml)

SD

Endemic area, full term

54

8.8

4.8

15.37

8.20

Non-endemic area, full term

73

10.0

2.9

11.93

4.99

Athens, full term

98

10.3

3.3

10.96

6.33

Source: Beckers et al., 1981

The report notes that "there are some countries where endemic
goitre is still prevalent when the country is regarded as a whole". This
applies, for instance, to the Federal Republic of Germany and the German
Democratic Republic.

In other countries - Spain, Portugal, Prance, Italy, Greece,
Romania, Turkey, Poland and Yugoslavia - regional goitrous areas are well
documented. This may also apply to Belgium, Denmark, Great Britain, Ireland and
the Soviet Union. Further epidemiological studies are strongly recommended for
some of these countries.

The report notes the large sums of money spent for the
diagnosis and treatment of thyroid diseases in Europe, e.g. DM 308m for
outpatient diagnosis and medical treatment of thyroid disorders in the Federal
Republic of Germany in 1979. This money is mainly for the surgical expenses
because of goitre and its complications. There is therefore a cost benefit to be
gained from effective iodization programmes.

Conclusion

The persistence of the IDD problem in Europe, a continent of
generally rich countries, is remarkable when control measures are readily
available and affordable. There should be no further delay in setting up
programmes aimed at eradicating them.

3.2 AMERICAN REGION

A recent report (Noguera et al., 1983, revised in 1984)
notes that "Iodine deficiency and endemic goitre are still a problem in many
countries in Latin America. In Bolivia, Ecuador and Peru cretinism is a frequent
syndrome associated with higher prevalences of endemic goitre". It goes on to
note that while there are legal provisions for the iodization of salt, these are
not adequately carried out. There is also a need for educational programmes. A
tabulation of detailed data on goitre prevalence and urinary iodine levels for
all countries in Central and South America is provided in the report and is
reproduced in Table 8. Further data are available in the recent PAHO/WHO
monograph from the meeting in Lima, Peru (Dunn et al., 1986).

Conclusion

The tabulations indicate persistence of goitre in school
children at a prevalence of over 10 percent in all countries with the exception
of Costa Rica, Cuba and Uruguay. Urinary iodine levels are in the range 25 - 90
mcg/g of creatinine. A more effective iodization programme is clearly needed in
all these countries.

TABLE 8

STUDIES ON ENDEMIC GOITRE PREVALENCE IN LATIN AMERICA
(PAHO)

Country (year)

Type of population Studied

Population sampled

Size of sample

Method of goitre classification

Overall prevalence

Argentina

1967

Sch/children

Departmental

4,431

Perez & Scrimshaw

49.8

(12.5-61.9)

1967

20 years

Departmental

47,679

Perez & Scrimshaw

15.6

(4.3-53.6)

Bolivia

1976

Sch/children

La Paz

4,200

WHO modified

68

1979

Sch/children

Pando

680

WHO modified

77

1981

Sch/children

National

38,500

WHO adapted

60.8

Observation: WHO classification adjusted
locally

Brazil

1966

Sch/children

45 municips.

45,924

27.2

1967

Sch/children

41 municips.

48,443

21.9

1975

Sch/children

National

266,373

WHO adapted*

14.7

Observation: *Only the inspection criterion was
considered

Chile

1972

General

Community

8,407

Perez & Scrimshaw

24.8

Colombia

1945

Sch/children

National

183,243

Old classification

53

Observation: 385 municipalities examined

1945

Sch/children

Departmental

8,062

Old classification

83.1

Observation: 8 municipalities examined

1952

Sch/children

Departmental

6,511

Old classification

33.9

1965

Sch/children

Departmental

12,166

Old classification

1.8

Observation: In 1952 and 1965 the same municipal!tes
were examined

Costa Rica

1966

General

National

4,065

Perez & Scrimshaw

18.0

1979

Sch/children

National

5,061

Perez & Scrimshaw

3.5

Cuba

1974

6-20 years

Baracoa

2,664

Perez & Scrimshaw

30.0

1976

General

Habana

6,149

Perez & Scrimshaw

3.4

Ecuador

1969

Sch/children

National

28,639

Perez & Scrimshaw

23.7

1978

Sch/children

National

36,962

Perez & Scrimshaw

12.0

Observation: In 1969 and 1978 the same localities were
examined.

El Salvador

1966

General

National

3,231

Perez & Scrimshaw

48.0

Guatemala

1949

General

National

4,113

Old Classification

38.0

1965

General

National

2,995

Perez & Scrimshaw (Original)

5.2

1979

Sch/children

National

3,654

Perez & Scrimshaw

10.5

Honduras

1966

General

National

3,654

Perez & Scrimshaw

17.0

Mexico

1950

General

8 states

1,000,000

54.6

Nicaragua

1966

General

National

3,477

Perez & Scrimshaw

32.0

1977

General

National

13,814

Perez & Scrimshaw

33.0

1981

General

National

6,252

Perez & Scrimshaw

20.0

Panama

1967

General

National

3,071

Perez & Scrimshaw

16.5

1975

General

National

4,084

Perez & Scrimshaw

6.0

Paraguay

1976

General

National

4,078

Perez & Scrimshaw

18.1

1980

Maternal/ child

3 communities

343

WHO modified

23.6

1982

Sch/children

6 communities

420

WHO modified

16.40

Peru

1968

Sch/children

National

181,118

Perez & Scrimshaw

22.0

1976

General

National

9,293

WHO modified

15.0*

Observation: *Average prevalence in mountains, jungle and
coast

Uruguay

1973

Sch/Children

Departmental

2,515

Perez & Scrimshaw

9.0

1980

Sch/Children

Departmental

1,245

Perez & Scrimshaw

2.0

Venezuela

1966

Sch/Children

National

470,207

Perez & Scrimshaw

13.0

1981

Sch/children

& adolescents

National

14,709

WHO modified

21.37

Source: Noguera et al., 1984Note: Municips. = Municipalities

3.3 AFRICAN REGION

1. Goitre. Practically all countries of the
region have significant goitrous areas and in some of them the problem is
severe, e.g. 85 percent of female children aged 11-15 years in East Cameroon had
palpable goitres of grades 1 to 3 (see Table 9).

2. Control is relatively easy from the
technological viewpoint, by

a) iodized salt;b) injecting iodized oil (every five years).

The strategy proposed by the WHO Africa Regional
Office is to iodate salt where feasible within the country, preferably at
national or provincial level, and (simultaneously or afterwards) deal with the
remaining pockets by injections of iodized oil.

For most countries what is lacking is the political will,
backing, and financial resources for the necessary intersectoral action, since
the Implementation of such a programme necessitates at least the cooperation of
the Ministries of Health, Trade and Commerce, Finance and sometimes other
specialized bodies (laboratories for quality control of iodated salt,
etc.).

More detailed data from Algeria, Zaire and Senegal have
recently been published (Benmiloud and Ermans, 1986). The roles of retinol
deficiency in Senegal and cassava consumption in Zaire have been identified as
exacerbating the effects of iodine-deficiency. The fragmentary nature of the
data from east, central and southern Africa has been pointed out (Volde-Gebriel,
1986).

Difficulties in Tanzania mentioned by Kavishe et al.
(1981) include defining the magnitude of the problem, lack of laboratory
facilities, the technology and organization of salt iodization at sector level,
manpower and staff training. Recent data are given by Ekpechi (1987).

It seems likely that there is a high prevalence of goitre
throughout the extensive southern Africa plateau which includes large areas of
Zimbabwe, Zambia, Botswana and Mozambique, all of which have substantial IDD
problems. In Zimbabwe, cretinism has been seen only in the more remote eastern
highlands, justifying overall classification of the IDD problem as
moderate.

In general, only fragmentary data are available for Africa and
technical resources are severely limited. More attention to the IDD problem in
Africa is urgently required. In southern Africa salt iodization could be an
effective solution. In more severe endemias such as Zaire iodized oil has been
used and will probably need to be continued. Many other countries fall between
these extremes.

3.4 SOUTHEAST ASIAN
REGION

This region has a major IDD problem in eight countries (See
Table 6). Estimates are given in Table 10 and point to the large numbers of
people affected, living in areas of defined environmental iodine deficiency
where prevalence of goitre is more than 10 percent of the population. A full
report is now available (Clugston and Bagchi, 1985).

TABLE 10

ESTIMATED POPULATIONS AT RISK AND PREVALENCE OF ENDEMIC
GOITRE IN EIGHT COUNTRIES OF THE WHO SOUTHEAST ASIAN REGION (numbers in
thousands)

Country

Total POP.

Population at risk (TGR > 10%)

Endemic goitre prevalence

Number

%

Number

%

Bangladesh

97 438

37 150

38.1

10 225

10.5

Bhutan

1 446

1 466

100.

946

65.4

Burma

39 920

14 545

36.5

5 694

14.3

India

746 010

149 588

20.0

7.3

Indonesia

161 003

29 773

18.5

9 759

6.1

Nepal

16 386

15 099

92.0

7 555

46.1

Sri Lanka

16 099

10 565

65.6

3 112

19.3

Thailand

52 709

20 439

38.8

7 740

14.7

TOTAL

1 131 011

278 605

24.6

99 349

8.8

Note:

TGR = Total Goitre Rate (prevalence)Percentages shown are percentages of
total population

Source: Clugston and Bagchi (1985, p. 14) and for total
population data UN Demographic Yearbook 1981/1982

An important indication of the severity of IDD is given by
determinations of blood T-4 and TSH on cord blood samples from neonates in
Gonda, Uttar Pradesh, as compared with New Delhi (Table 11). These data indicate
a 4 percent rate of neonatal hypothyroidism.

Follow-up is required in order to evaluate the persistence of
such rates and to determine whether these infants are likely to develop
permanent brain damage. A preventive programme is urgently needed (preferably
with iodized oil).

The persistence of goitre in the face of a national iodized
salt programme in India has been well documented by the Ministry of Health
(Table 12). The findings show the need to monitor the iodization programme and
urgently consider remedial measures, including the possible use of alternative
technology. (See Section 6).

Conclusion

The largest populations living in iodine-deficient
environments and therefore at risk of IDD are to be found in Asia. There is an
enormous opportunity to improve quality of life and productivity by correcting
iodine deficiency in these countries.

TABLE 12

IMPACT OF IODIZATION PROGRAMMES IN INDIA

District/ state

Baseline survey year

Prevalence percentage rate

Commencement of salt supply

Resurvey year

Prevalence percentage rate

HIMACHAL PRADESH

Sirmoor

1959

35.8

1963

1980

28.07

Kangra

1956

41.2

1962

1962

32.10

PUNJAB

Gurdaspur

1961

52.3

1964

1969

42.30

Hoshiarpur

1961

40.3

1964

1969

23.60

Chandigarh

1969

11.2

1968

1977

45.90

BIHAR

Champaran(East and West)

1960

40.3

1964

1979

64.51(East)

57.20(West)

WEST BENGAL

Darjeeling

1965

34.5

1967

1975-76

35.58

UTTAR PRADESH

Dehra Dun

1965

39.7

1966

1969

16.90

Bijnore

1960

23.2

1960

1969

23.60

Source: Nutrition Foundation of India,
1983

3.5 WESTERN PACIFIC
REGION

A report from China indicates a massive problem with about 30
percent of the population at risk of IDD (Table 13). Effective programmes have
been operating since 1978. In that time, it was claimed that IDD have been
completely controlled in six of 27 provinces (mainly with iodized salt), but in
another 11 provinces the programmes, although started, have not yet been
adequately established and shown (through monitoring) to be effective. There are
about 10 million people in Xinjiang and Tibet who need an iodized oil programme,
but transportation in these provinces is very difficult (Ma, 1984). Limited data
from Vietnam, Laos and Kampuchea indicate that severe IDD exist. (See Table
6).

TABLE 13

EXTENT AND EFFECT OF IODIZATION PROGRAMMES IN THE
PEOPLE'S REPUBLIC OF CHINA

1984:
270,000,000 Some 60,000,000 people at risk not covered by iodization programmes

Among the 27 provinces with IDD endemia:
1. IDD controlled in 6 provinces by 1984.
2. Iodization programmes not well established in 11 provinces by 1984.

Although 310,000,000 are at risk of IDD under iodization programmes more
than one third are not well quantified. Modern monitoring systems lacking
to guarantee the quality of iodization programmes

1984:
330,000,000 Still some China provinces not included

Additional iodized oil injections for young married women in certain
areas

Source: Ma Tai, 1984 Conclusion

China has made remarkable progress with salt iodization since
1978. This indicates the priority of prevention in the country's political
philosophy. (See Sections 6 and 8).

3.6 GENERAL CONCLUSIONS

These data indicate a massive global problem. Where IDD have
disappeared in Western countries, this has been brought about by an increased
dietary intake of iodine either through specific supplementation with iodized
salt or by dietary diversification as one of the outcomes of economic
development. The problem can be expected to persist in the absence of either of
these factors. Therefore the effects of iodine deficiency in the form of IDD on
growth and development (Section 2) will continue to be evident. National and
international action is indicated. Priority should be given to those areas and
regions where the persistence of severe IDD can be anticipated as already
pointed out in Section 1.